Light emitting diode with improved current spreading performance

ABSTRACT

Disclosed is a light emitting diode (LED) for enhancing the current spreading performance. The LED includes a plurality of contact holes exposing an N-type semiconductor layer through a P-type semiconductor layer and an active layer, and a connection pattern electrically connecting exposed portions of the N-type semiconductor layer through the contact holes, thereby enhancing current spreading in the N-type semiconductor layer. In addition, disclosed is an LED including a plurality of light emitting cells spaced apart from one another on an N-type semiconductor layer and an N-contact layer between the light emitting cells. A plurality of light emitting cells are employed in the LED, so that current can be spread in the LED.

CROSS REFERENCE RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2007-0080496, filed on Aug. 10, 2007, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting diode, and moreparticularly, to a light emitting diode wherein the luminous efficiencyis improved by enhancing current spreading performance.

2. Description of the Related Art

GaN-based light emitting diodes (LEDs) have considerably changed LEDtechnologies and are currently used in a variety of applications such asfull-color LED displays, LED traffic lights and white LEDs. Recently,high-efficiency white LEDs are expected to replace fluorescent lamps.Particularly, the efficiency of the white LEDs has reached a levelsimilar to that of general fluorescent lamps.

A GaN-based LED is generally formed by growing epitaxial layers on asubstrate such as sapphire, and comprises an N-type semiconductor layer,a P-type semiconductor layer and an active layer interposedtherebetween. An N-electrode is formed on the N-type semiconductorlayer, and a P-electrode is formed on the P-type semiconductor layer.The LED is electrically connected to an external power source throughthe electrodes to thereby be driven. At this time, current flows fromthe P-electrode into the N-electrode via the semiconductor layers.

Since the P-type semiconductor layer generally has a high specificresistivity, current is not uniformly distributed in the P-typesemiconductor layer but concentrated on a portion at which theP-electrode is formed. In addition, the current flows into theN-electrode via the semiconductor layers. Accordingly, the current isconcentrated on a portion at which the N-electrode is formed on theN-type semiconductor layer, and there is a problem in that the currentconcentratedly flows through an edge of the LED. The currentconcentration leads to reduction of a light emitting area, andtherefore, the luminous efficiency is lowered.

Such a problem is very serious in a large-sized LED of about 1 mm² ormore, particularly used for high luminosity. That is, since current isnot spread over a central portion of the LED but mostly flows through acorner or edge of the LED, the luminous efficiency is relatively reducedin the large-sized LED.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an LED, wherein thecurrent flowing through P-type and N-type semiconductor layers can beuniformly spread.

Another object of the present invention is to provide an LED, whereinthe luminous efficiency is improved by decentralizing regions on whichcurrent is concentrated in the LED.

According to the present invention for achieving the objects, there isprovided an LED having improved current spreading performance. An LEDaccording to an aspect of the present invention comprises an N-typesemiconductor layer, a P-type semiconductor layer, and an active layerinterposed between the N-type and P-type semiconductor layers. Aplurality of contact holes expose the N-type semiconductor layer throughthe P-type semiconductor layer and the active layer. Further, aP-contact layer is formed on the P-type semiconductor layer. Inaddition, a connection pattern is formed in the contact holes and on theP-contact layer. The connection pattern electrically connects theexposed portions of the N-type semiconductor layer in the contact holesto one another. An insulating layer is interposed between the P-contactlayer and the connection pattern and between sidewalls of the contactholes and the connection pattern. The connection pattern is electricallyconnected to various portions of the N-type semiconductor layer, therebyenhancing the current spreading performance. In addition, the P-typesemiconductor layer and the active layer are removed, so that a regionat which the N-type semiconductor layer is exposed can be reduced,thereby increasing the region in which light is generated, i.e., theactive layer.

Meanwhile, N-contact layers may be interposed between the connectionpattern and the exposed portions of the N-type semiconductor layer inthe contact holes. The N-contact layers may be in ohmic-contact with theN-type semiconductor layer to thereby lower contact resistance.

In the meantime, the plurality of contact holes may be regularlyarranged. The arrangement of the plurality of contact holes is notparticularly limited. For example, the plurality of contact holes may bearranged in the form of a beehive or matrix.

The connection pattern may connect the plurality of contact holes in aline shape, and an upper region of the P-contact layer may bepartitioned into a plurality of regions by the connection pattern. Inaddition, P-bumps are formed in the partitioned regions and electricallyconnected to the P-contact layer.

Further, N-bumps may be formed on the connection pattern. For example,the connection pattern may include an N-bump region positioned at anedge of the LED, and the N-bumps may be formed on the N-bump region.

Meanwhile, some of the plurality of contact holes may be positionedunder the N-bump region. These contact holes help light to be generatedeven at a lower portion of the N-bump region.

The LED may emit blue light or ultraviolet light, and materials of theN-type and P-type semiconductor layers and the active layer may beselected to emit light of desired wavelength. For example, the activelayer may include a well layer of In_(x)Al_(y)Ga_(1−x−y)N (0≦x<1, 0≦y<1,0≦x+y<1), and a composition ratio of x and y may be selected to emitlight of desired wavelength.

An LED according to another aspect of the present invention includes anN-type semiconductor layer having a cell region and an N-electroderegion around the cell region. A plurality of light emitting cells arepositioned on the cell region of the N-type semiconductor layer to bespaced apart from one another. Each of the light emitting cellscomprises a P-type semiconductor layer and an active layer interposedbetween the N-type and P-type semiconductor layers. A P-contact layer isformed on the P-type semiconductor layer of each light emitting cell.Further, an N-contact layer is spaced apart from the light emittingcells and formed on the N-type semiconductor layer in the N-electroderegion and the N-type semiconductor layer between the light emittingcells. In addition, a P-connection layer is formed over the cell regionto electrically connect the P-contact layers to one another. Aninsulating layer is interposed between the P-connection layer andsidewalls of the light emitting cells and between the P-connection layerand the N-contact layer. A plurality of light emitting cells spacedapart from one another are employed, and an N-contact layer is formedbetween the light emitting cells, so that the current concentrated on anedge of the conventional LED can be spread edges of the light emittingcells, thereby enhancing the current spreading performance of the LED.

Meanwhile, N-bumps may be formed on the N-contact layer positioned onthe N-electrode region, and P-bumps may be formed on the P-connectionlayer. Accordingly, there is provided an LED to which flip-chip bondingcan be applied.

In addition, the N-electrode region may surround the cell region. Thus,the current that flows into the cell region can be spread over a broadregion.

Meanwhile, the P-bumps are formed on the light emitting cells,respectively. Accordingly, the current that flows into the lightemitting cells can be uniformly spread.

In the meantime, the light emitting cells may be regularly arranged, forexample, in the form of a beehive or matrix.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating an LED according to an embodiment ofthe present invention;

FIG. 2 is a sectional view taken along line A-A of FIG. 1;

FIG. 3 is a sectional view taken along line B-B of FIG. 1;

FIG. 4 is a sectional view taken along line C-C of FIG. 1;

FIG. 5 is a plan view illustrating an example of a submount on which theLED can be mounted according to the embodiment of the present invention;

FIG. 6 is a plan view illustrating an LED according to anotherembodiment of the present invention;

FIG. 7 is a sectional view taken along line A-A of FIG. 6;

FIG. 8 is a sectional view taken along line B-B of FIG. 6; and

FIG. 9 is a sectional view taken along line C-C of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Thefollowing embodiments are provided only for illustrative purposes sothat those skilled in the art can fully understand the spirit of thepresent invention. Therefore, the present invention is not limited tothe following embodiments but may be implemented in other forms. In thedrawings, the widths, lengths, thicknesses and the like of elements maybe exaggerated for convenience of illustration. Like reference numeralsindicate like elements throughout the specification and drawings.

FIG. 1 is a plan view illustrating an LED according to an embodiment ofthe present invention. FIGS. 2, 3 and 4 are sectional views taken alonglines A-A, B-B and C-C of FIG. 1, respectively.

Referring to FIGS. 1 to 4, an N-type semiconductor layer 23 is formed ona substrate 21. The substrate 21 is a substrate allowing light to passtherethrough and may be, for example, an AlN, SiC or sapphire substrate.In addition, the substrate 21 may have a bottom surface patterned inorder to increase light extraction efficiency. A P-type semiconductorlayer 27 is formed on the N-type semiconductor layer 23, and an activelayer 25 is interposed between the N-type and P-type semiconductorlayers 23 and 27.

The N-type semiconductor layer 23, the active layer 25 and the P-typesemiconductor layer 27 may be formed of a GaN-based compoundsemiconductor material, i.e., (Al, In, Ga)N. Composition elements and acomposition ratio of the active layer 25 are determined to emit light ofdesired wavelength, e.g., ultraviolet light or blue light. The N-typesemiconductor layer 23 and/or the P-type semiconductor layer 27 areformed of a material with a band gap greater than that of the activelayer 25.

The N-type semiconductor layer 23 and/or the P-type semiconductor layer27 may be formed to have a single layer structure as shown in thesefigures or may be formed to have a multi-layer structure. For example,the N-type semiconductor layer 23 may include an N-clad layer adjacentto the active layer 25, and the P-type semiconductor layer 27 mayinclude a P-clad layer adjacent to the active layer 25. When the N-typeor P-type semiconductor layer is formed to have a multi-layer structure,the N-type or P-type semiconductor layer may include a layer which isnot intentionally doped. In the meantime, the active layer 25 may have asingle quantum well structure or a multiple quantum well structure. Abuffer layer (not shown) may be interposed between the substrate 21 andthe N-type semiconductor layer 23. The buffer layer is employed toreduce lattice mismatch between the substrate 21 and the N-typesemiconductor layer 23 formed thereon. The semiconductor layers 23, 25and 27 may be formed by a metal organic chemical vapor deposition(MOCVD) or molecular beam epitaxy (MBE) technique, and may beconsecutively formed in a single chamber.

Meanwhile, a plurality of contact holes 35 h expose the N-typesemiconductor layer 23 through the P-type semiconductor layer 27 and theactive layer 25. The contact holes 35 h are spaced apart from oneanother and arranged so that the exposed portions of the N-typesemiconductor layer 23 are uniformly distributed on the top surface ofthe substrate 21. The contact holes 35 h may be regularly arranged. Thecontact holes 35 h may be arranged in the form of a beehive or matrix asshown in FIG. 1 but not be limited thereto.

A P-contact layer 29 is formed on the P-type semiconductor layer 27. TheP-contact layer 29 is in ohmic-contact with the P-type semiconductorlayer 27 to thereby lower contact resistance. The P-contact layer 29 maybe formed of a transparent conductive layer such as ITO or Ni/Au, but isnot limited thereto. That is, the P-contact layer 29 may be formed ofvarious materials that are in ohmic-contact with the P-typesemiconductor layer 27, e.g., a metal, alloy or metal oxide. In someembodiments, the P-contact layer 29 may include a reflective metal thatreflects light emitted from the active layer 25. Accordingly, the lightemitted toward the P-contact layer 29 from the active layer is reflectedtoward the substrate 21 and then emitted to the outside. In someembodiments, the P-contact layer 29 may be formed to be relativelythick, so that current spreading can be easily achieved in the P-contactlayer 29.

The P-contact layer 29 may be formed on the entire region of the P-typesemiconductor layer 27 except the contact holes 35 h, and may bepositioned to be slightly distant from the contact holes 35 h as shownin these figures.

Meanwhile, sidewalls of the contact holes 35 h is covered with aninsulating layer 33. The insulating layer 33 has openings that exposeportions of the N-type semiconductor layer 23 exposed by the contactholes 35 h. Further, the insulating layer 33 may extend over the P-typesemiconductor layer 27 and only have openings for exposing portions ofthe P-contact layer 29. The insulating layer 33 may be formed of siliconoxide or silicon nitride by a chemical vapor deposition (CVD) technique.Alternatively, the openings may be formed by patterning a depositedinsulating layer using a photolithography technique.

N-contact layers 31 are formed on the portions of the N-typesemiconductor layer 23 that are exposed by the contact holes 35 h. TheN-contact layers 31 are in ohmic-contact with the N-type semiconductorlayer 23 to thereby lower contact resistance. The N-contact layers 31are spaced apart from the active layer 25 and the P-type semiconductorlayer 27, for example, by the insulating layer 33.

Meanwhile, a connection pattern 35 is formed in the contact holes 35 hand on the P-contact layer 29 to connect the N-contact layers. Theconnection pattern 35 is formed of a conductive material, e.g., a metalor alloy. When the connection pattern 35 is formed of a material that isin ohmic-contact with the N-type semiconductor layer 23, the N-contactlayers 31 may be omitted. That is, the connection pattern 35 may be indirect contact with the portions of the N-type semiconductor layer 23exposed through the contact holes 35 h.

The connection pattern 35 is insulated from the P-type semiconductorlayer 27, the active layer 25 and the P-contact layer 29 by means of theinsulating layer 33. As shown in FIG. 1, the connection pattern 35 mayconnect the plurality of contact holes 35 h linearly. An upper region ofthe P-contact layer 29 is partitioned into a plurality of regions by theconnection pattern 35. Particularly, when the contact holes 35 h areregularly arranged, the upper region of the P-contact layer 29 ispartitioned in a regular pattern. For example, when the contact holes 35h are arranged in a matrix form, the upper region of the P-contact layer29 is partitioned into quadrangle regions as shown in FIG. 1.

P-bumps 37 may be formed in the partitioned regions. The P-bumps 37 areelectrically connected to the P-contact layer 29. Although a singleP-bump 37 may be formed, the P-bumps 37 are respectively formed in thepartitioned regions, so that current can be easily spread and theP-contact layer 29 can be formed to be relatively thin.

Meanwhile, N-bumps 39 may be formed on the connection pattern 35. Forexample, as shown in FIG. 1, the connection pattern 35 may include anN-bump region positioned at edges of the LED, and the N-bumps 39 areformed on the N-bump region. The N-bumps 39 are electrically connectedto the portions of the N-type semiconductor layer 23 exposed through thecontact holes 35 h. Thus, in order to form the N-bumps 39, it isunnecessary to remove the P-type semiconductor layer 27 and the activelayer 25 in the N-bump region. Accordingly, light can be generated evenunder the N-bump region in which the N-bumps 39 are formed. In order tosupply current to the N-type semiconductor layer 23 formed under theN-bump region, some of the plurality of contact holes may be positionedunder the N-bump region.

FIG. 5 is a plan view illustrating an example of a submount on which theLED of FIG. 1 can be mounted.

Referring to FIG. 5, the submount comprises a substrate 41, and aP-electrode 43 and an N-electrode 45 on the substrate 41, which areelectrically separated from each other. The substrate 41 may be formedof a material with high thermal conductivity, such as silicon or AlN, ora metallic material having an insulating layer formed thereon. TheP-electrode 43 includes a region 43 p to which the P-bumps 37 of the LEDadhere, and the N-electrode 45 includes a region 45 n to which theN-bumps 39 of the LED adhere. The LED of FIG. 1 is flip-bonded to thesubmount. Bonding wires are bonded to the P-electrode 43 and theN-electrode 45, so that the LED is electrically connected to an externalpower source.

FIG. 6 is a plan view illustrating an LED according to anotherembodiment of the present invention. FIGS. 7, 8 and 9 are sectionalviews taken along lines A-A, B-B and C-C of FIG. 6, respectively.

Referring to FIGS. 6 to 9, an N-type semiconductor layer 53 is formed ona substrate 51. The substrate 51 may be the same substrate as describedwith reference to FIG. 1. The N-type semiconductor layer 53 has anN-electrode region positioned in and around a cell region. TheN-electrode region may be positioned on at least one edge of thesubstrate 51. As shown in FIG. 6, the cell region may be positioned atthe center of the substrate 51, and the N-electrode region may surroundthe cell region.

A plurality of light emitting cells 56 are spaced apart from one anotheron the cell region of the N-type semiconductor layer 53. Each of thelight emitting cells 56 comprises a P-type semiconductor layer 57 and anactive layer 55 interposed between the N-type semiconductor layer 53 andthe P-type semiconductor layer 57. The light emitting cells 56 may beformed by growing the active layer and the P-type semiconductor layer onthe N-type semiconductor layer 57 and then patterning the P-typesemiconductor layer and the active layer by a photolithographytechnique.

Meanwhile, the N-type semiconductor layer 53, the active layer 55 andthe P-type semiconductor layer 57 may be formed of a GaN-based compoundsemiconductor material, i.e., (Al, In, Ga)N as described with referenceto FIGS. 1 to 4. Composition elements and a composition ratio of theactive layer 25 are determined to emit light of desired wavelength,e.g., ultraviolet light or blue light. The N-type semiconductor layer 53and/or the P-type semiconductor layer 57 are formed of a material with aband gap greater than that of the active layer 25.

The N-type semiconductor layer 53 and/or the P-type semiconductor layer57 may be formed to have a single layer structure as shown in thesefigures or may be formed to have a multi-layer structure as describedwith reference to FIGS. 1 to 4. The active layer 55 may have a singlequantum well structure or a multiple quantum well structure. A bufferlayer (not shown) may be interposed between the substrate 51 and theN-type semiconductor layer 53.

Meanwhile, the light emitting cells 56 may be regularly arranged, forexample, in the form of a beehive or matrix. As the light emitting cells56 are positioned on the N-type semiconductor layer 53 to be spacedapart from one another, grooves 61 g that expose the N-typesemiconductor layer 53 are formed between the light emitting cells 56.When the light emitting cells 56 are arranged in a matrix form, thegrooves 61 g are formed in transversal and longitudinal directionsbetween the light emitting cells 56 as shown in FIG. 6.

In the meantime, a P-contact layer 59 is formed on the P-typesemiconductor layer 57 of each of the light emitting cells 56. TheP-contact layers 59 are positioned to be confined on upper portions ofthe light emitting cells 56, thereby being spaced apart from each other.After the respective light emitting cells 56 are formed, the P-contactlayers 59 may be formed on the P-type semiconductor layer 57, which isnot limited thereto but may be previously formed on the P-typesemiconductor layer before the P-type semiconductor layer and the activelayer are patterned by a photolithography technique. The P-contact layer59 is in ohmic-contact with the P-type semiconductor layer 57 to therebylower contact resistance. The P-contact layer 59 may be the samematerial as described with reference to FIGS. 1 to 4 and include areflective metal.

In addition, N-contact layers 61 are formed between the N-electroderegion and the light emitting cells 56, i.e., on the N-typesemiconductor layer 57 in grooves 65 g. The N-contact layer 61 is inohmic-contact with the N-type semiconductor layer 53 to thereby lowercontact resistance. The N-contact layers 61 formed in the N-electroderegion and the grooves 65 g are electrically connected to one anotherand spaced apart from the light emitting cells 56.

Meanwhile, sidewalls of the light emitting cells 56 and the N-contactlayers 61 formed in the grooves 65 g are covered with an insulatinglayer 63. The insulating layer 63 may extend over the P-typesemiconductor layers 57 and only have openings for exposing portions ofthe P-contact layers 59. The insulating layer 63 may be formed of asilicon oxide or silicon nitride by a CVD technique.

A P-connection layer 65 is formed on the cell region to electricallyconnect P-contact layers 59 to one another. The P-connection layer 65 isformed over the light emitting cells 56 and the grooves 65 g. As shownin these figures, the P-connection layer 65 may be formed in the grooves65 g. However, the insulating layer 63 is interposed between theP-connection layer 65 and the N-contact layer 61 to insulate them fromeach other. In addition, the P-connection layer 65 is spaced apart fromthe sidewalls of the light emitting cells 56 by the insulating layer 63.The P-connection layer 65 may be formed of a conductive material, e.g.,a metal or alloy.

Meanwhile, P-bumps 67 are formed on the P-connection layer 65. A singleP-bump may be formed on the P-connection layer 65, which is not limitedthereto. That is, a plurality of P-bumps 65 may be formed on theP-connection layer 65. At this time, the P-bumps 65 may be positionedabove the light emitting cells 56, respectively. Accordingly, currentthat flows into the light emitting cells 56 can be easily spread.

In addition, N-bumps 69 are formed on the N-contact layer 61 in theN-electrode region. A single N-bump may be formed, which is not limitedthereto. In particular, a plurality of N-bumps may be formed around thecell region to help current to spread. In addition, before the N-bumps69 are formed, an N-connection layer 64 may be formed on the N-contactlayer 61 formed on the N-electrode region. The N-connection layer 64functions as a pad that helps a current to spread and forms the N-bumps69 thereon. The N-connection layer 64 may be simultaneously formed whileforming the P-connection layer 65, for example, by a lift-off process.

The arrangement of the N-bumps on the N-electrode region may be changeddepending on the electrode structure of a submount for mounting an LEDthereon. For example, an N-electrode region surrounding a cell region isshown in FIG. 6, and the N-bumps 69 are not formed at one edge of theN-electrode region. When the LED of this embodiment is mounted on asubmount (see FIG. 5) having a P-electrode and an N-electrode separatedfrom each other, the N-bumps 69 are prevented from being in contact withthe P-electrode.

In this embodiment, the N-bumps 69 are electrically connected to theN-contact layer 61 formed in the grooves 65 g through the N-contactlayer 61 on the N-electrode region. Accordingly, current can be spreadover the portions of the N-type semiconductor layer 53 positioned aroundeach light emitting cell 56. Further, a plurality of light emittingcells are employed to thereby increase the length of the edges of anLED, on which current is concentrated, so that the current spreadingperformance of the LED can be enhanced.

According to the embodiments of the present invention, there is providedan LED for uniformly spreading current that flows through P-type andN-type semiconductor layers. Further, a plurality of light emittingcells are employed, so that regions on which a current is concentratedin the LED are decentralized, and therefore, the luminous efficiency canbe improved. In addition, a plurality of contact holes are employed, sothat the current spreading performance can be enhanced without reducingregions at which light is emitted as compared with a conventional LED.

1. A light emitting diode (LED), comprising: an N-type semiconductorlayer; a P-type semiconductor layer; an active layer interposed betweenthe N-type and P-type semiconductor layers; a plurality of contact holesexposing the N-type semiconductor layer through the P-type semiconductorlayer and the active layer; a P-contact layer formed on the P-typesemiconductor layer; a connection pattern formed in the contact holesand on the P-contact layer to electrically connect exposed portions ofthe N-type semiconductor layer in the contact holes to one another; andan insulating layer interposed between the P-contact layer and theconnection pattern and between sidewalls of the contact holes and theconnection pattern.
 2. The LED as claimed in claim 1, further comprisingN-contact layers interposed between the connection pattern and theexposed portions of the N-type semiconductor layer in the contact holes.3. The LED as claimed in claim 1, wherein the plurality of contact holesare regularly arranged.
 4. The LED as claimed in claim 3, wherein theplurality of contact holes are arranged in a matrix form.
 5. The LED asclaimed in claim 3, wherein the connection pattern connects theplurality of contact holes in a line shape, and an upper region of theP-contact layer is partitioned into a plurality of regions by theconnection pattern.
 6. The LED as claimed in claim 5, further comprisingP-bumps formed in the partitioned regions and electrically connected tothe P-contact layer.
 7. The LED as claimed in claim 5, furthercomprising N-bumps formed on the connection pattern.
 8. The LED asclaimed in claim 7, wherein the connection pattern includes an N-bumpregion positioned at an edge of the LED, and the N-bumps are formed onthe N-bump region.
 9. The LED as claimed in claim 8, wherein some of theplurality of contact holes are positioned under the N-bump region. 10.The LED as claimed in claim 1, wherein the LED emits ultraviolet light.11. An LED, comprising: an N-type semiconductor layer having a cellregion and an N-electrode region around the cell region; a plurality oflight emitting cells spaced apart from one another on the cell region ofthe N-type semiconductor layer, each of the light emitting cells havinga P-type semiconductor layer and an active layer interposed between theN-type and P-type semiconductor layers; a P-contact layer formed on theP-type semiconductor layer of each of the light emitting cells; anN-contact layer spaced apart from the light emitting cells and formed onthe N-type semiconductor layer in the N-electrode region and the N-typesemiconductor layer between the light emitting cells; a P-connectionlayer formed over the cell region to electrically connect the P-contactlayers to one another; and an insulating layer interposed between theP-connection layer and sidewalls of the light emitting cells and betweenthe P-connection layer and the N-contact layer.
 12. The LED as claimedin claim 11, further comprising N-bumps formed on the N-contact layer onthe N-electrode region, and P-bumps formed on the P-connection layer.13. The LED as claimed in claim 12, wherein the N-electrode regionsurrounds the cell region.
 14. The LED as claimed in claim 12, whereinthe P-bumps are formed on the light emitting cells, respectively. 15.The LED as claimed in claim 11, wherein the light emitting cells areregularly arranged.
 16. The LED as claimed in claim 15, wherein thelight emitting cells are arranged in a matrix form.